Notes

This skill is great for energy recovery if you are fighting close to the frontlines. It not only recovers up to 27 energy for a mere cost of 5 energy (22 energy gain), it also drains up to 9 energy from an opponent.

Keep in mind that draining a target with 0 energy will not restore your own energy: you only gain energy for the amount of energy you are actually able to drain.

Energy Gain

This presumes Energy Drain is cast as often as possible (activation + recharge time) before any activation/recharge time modifiers, and that the target has at least the amount of energy drained.